diff --git a/test/CFrontend/2004-02-13-Memset.c b/test/CFrontend/2004-02-13-Memset.c
index ca0db7a..a12639c 100644
--- a/test/CFrontend/2004-02-13-Memset.c
+++ b/test/CFrontend/2004-02-13-Memset.c
@@ -1,4 +1,5 @@
-// RUN: %llvmgcc -xc %s -c -o - | llvm-dis | grep llvm.memset | wc -l | grep 3
+// RUN: %llvmgcc -xc %s -c -O1 -o - | llvm-dis | grep llvm.memset | \
+// RUN:   wc -l | grep 3
 
 void test(int* X, char *Y) {
   memset(X, 4, 1000);